Various means are well known in the art to close (i.e., stop, cork or seal) by means of threaded closure or stopper units in various containers and vessels, such as bottles, flasks or the like, having openings that are adapted or adaptable to receive same. Thus, especially when the container opening is pre-fabricated so as to have a threaded (particularly an interiorly threaded) neck portion, it is possible to employ for the closure a flexible capsule or sealing device which is insertable in the neck of the threaded container by merely knurling or turning the capsule under suitable inserting force or pressure into the pre-threaded neck opening of the container. Capsules or corks made of suitable plastic materials are particularly well adapted to be used as seals in this way since they are adapted to be securely screwed into the pre-threaded neck so as to provide an adequate seal or closure for the container. An alternative technique done in about the same way is to use a pre-threaded capsule or cork or the like closure device (also advantageously comprised of a suitable plastic material of construction) so as to even more positively assure the efficacious screwing of the stopper into the threaded neck opening of the container so as to make the desired seal.
In the first case, it is necessary at the time of stoppering to assure a pressure between the capsule or closure insert and the vessel so as to compress the container opening to effect the clossure and to maintain this compression during the time that the actual setting or the knurling of the capsule is being done.
On the other hand, when pre-threaded stoppers are employed, the joint or section which is at the bottom of the stopper is compressed at the end of the stoppering action so that it is not actually necessary to apply a vertical force on such a stopper during the container closing operation.
In several of the currently known container sealing machines, the stoppering and sealing devices used nonetheless exert a vertical force on even pre-threaded stoppers during the course of the sealing operation due to the fact that the tightening of the closure or stopper in the involved stoppering head (i.e., the element or section of the machine which actually effects and achieves the stopper inserting and resulting container closing and sealing operation) is a function of the force of applying the stoppper against the container bottle or the like container being stoppered or sealed so that, in order to assure the rotational movement of the stopper until a sufficient tightening torque has been applied for adequate sealing, it is generally necessary to employ a vertical force on the stopper during the stoppering operation. It has been found that the existence of this vertical force, particularly in cases where the threaded portion of the stopper has a relatively small pitch (i.e., a widely spaced threading), leads to functioning inconveniences and difficulties. For example, these may be manifest by a blockage or locking of the stopper on the threads of the container neck opening with which it is adapted and supposed to mate. This blockage tends to at least partially, if not completely, prevent the proper screwing on of the stopper and oftentimes subsequently causes later deteriorations and spoilage and/or leakage of contents of vessels thus imperfectly stoppered and sealed due to loss of contents from or entry of air into such poorly stoppered containers, especially during the course of transportation and other movement thereof.
A stoppering or sealing has also been heretofore suggested in which the stoppering head or closure performing element is supposedly adapted to assure lateral tightening of a pre-threaded stopper independently of the force applied by the stopper onto the container neck opening. In this machine, the stoppering head (or bottle closure inserting or applying) unit includes a piston which moves directionally parallel to the axis of the thread of the neck to be stopped. In this way, the piston acts during the closing on and in cooperation with a ring that is ordinarily made of a flexible rubbery or elastomeric material which presses against the side wall of the stopper during the actual closure of the container so as to permit rotational advancement of same without its being necessary for the stopper to have any vertical support force or pressure applied on the stopper and its associated neck. However, in such machine, the flexible ring which contacts and more or less encloses the stopper or closure element and which is subjected to the action of a piston is a one-piece affair which generally tends to deteriorate rather rapidly. It thus most often requires frequent replacement and therefore constitutes a great inconvenience and brings about distinct disadvantage in its use.